A decent scan tool would resolve all this guessing. The RCM really should be considered first as it may not throw a code and no one has mentioned the brake light switch as a possible solution, but that will code if scanned properly.

 

But the brake light switch does not explain the lack of speedometer. The failure of the RCM does.

 

So I had the Brake/abs/bas as well as no speedo and odometer. Additionally, the brake pad wear indicator was on and the wing was stuck up with the wing switch blinking. My battery was fine and my Rcm was recently repaired. I replaced the Abs module and all of these issues went away. $125 on eBay and the world was right again. Food for thought.

 

He stated

If the wheel abs sensor is cutting out but not dead then this might cause the vss to give that error since he stated his speedometer drops out at times not that its not working at all.

A good scan tool would find the problem I would imagine one way or the other. I know the one I have would since you can monitor the sensor and it will record drop outs if that is the problem.

 

Hello tighed1,do you know where the RCM is on my 2005 XF convertible? thank you

 

It's in the box next to the battery: